Uprightly-arranged support structure of protective fence

ABSTRACT

An uprightly-arranged support structure of a protective fence, the protective fence including: a plurality of supports arranged to stand at intervals, the plurality of supports having respective bottom portions thereof arranged to stand via a ground plate on a slope; and a protective net spread between the plurality of supports, wherein the bottom portions of the plurality of supports are arranged to stand so as to be slidable in conjunction with the ground plate in a predetermined direction on the slope.

CROSS REFERENCE TO RELATED APPLICATIONS

This is an application claiming priority, under the Paris Convention, onJapanese Patent Application No. 2018-133300 filed on Jul. 13, 2018, ofwhich full contents are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a protective fence arranged to stand ona slope of a mountain side, on such a slope at a bottom of themountainside, or the like, for capturing falling objects such as fallingrocks, earth and sand, and avalanches. In particular, the presentinvention relates to an uprightly-arranged support structure of theprotective fence of improved toughness and enhanced impact-absorptioncapability.

Description of the Background Art

In general, basic elements of a protective fence include a plurality ofsupports arranged to stand on a slope or the like at intervals, and aprotective net mounted between an adjacent pair of the plurality ofsupports. In the enhancement of the impact-absorption capability of theprotective fence, a shock absorber is placed in a portion of a ropemember of which the protective net is made, or in a portion of a stayrope for holding the plurality of supports.

Most protective nets are those made of wire meshes, metallic or fibrousrope members, or a combination thereof. Steel members such as H-shapedsteel or steel tube, concrete-filled steel tubes, concrete-filled steeltubes each having PC material embedded therein, and the like have beenknown for the plurality of supports. The material for the protective netand the plurality of supports has been selected in accordance with theimpact-absorption capability of the protective fence.

In general, a protective fence has a structure to receive finally by aplurality of supports, impact force of falling objects such as fallingrocks acting on a protective net and substantially on the plurality ofsupports. For this reason, such a structure having the plurality ofsupports arranged uprightly is important.

As an uprightly-arranged support structure, an embodiment having aplurality of supports arranged to stand in a non-inclinable manner, andan embodiment having a plurality of supports arranged to stand in aninclinable manner have been known.

As the embodiment having the plurality of supports arranged to stand ina non-inclinable manner, a further embodiment with the plurality ofsupports having their respective bottom portions rooted in a concretefoundation (Patent Document 1), and a still further embodiment with theplurality of supports having their respective bottom portions rooteddeep in the ground of a job site (Patent Document 2) have been known.

The embodiment having the plurality of supports arranged to stand in aninclinable manner, which is a structure with a support arranged to standinclinably on a ground plate without rooted in the ground, includes: afurther embodiment having a hinge element provided at a bottom portionof the support (Patent Documents 3, 4); and a still further embodimentwith a retention rope attached to an anchor for a support anchored intothe ground, and inserted through a ground plate and hollow support sothat an end of the retention rope is drawn out an upper end of thesupport and provided with a shock-absorbing metal fitting (PatentDocument 5).

The embodiment having the hinge element provided at the bottom portionof the support is configured such that a shock absorber is placed in aportion of a stay rope for a support, and as a result, such a stay ropemaintains the support in an upright manner under normal conditions, andslips so as to incline the support toward a valley side, by rotating thesupport around its hinge element, upon reception of impact.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Application Publication No.2003-034912 (FIG. 2)

Patent Document 2: Japanese Patent Application Publication No.2007-205109 (FIGS. 1, 3)

Patent Document 3: Japanese Patent Application Publication No.2007-032032 (FIGS. 1, 2)

Patent Document 4: Japanese Patent Application Publication No.2009-144472 (FIGS. 1, 7)

Patent Document 5: Japanese Patent Application Publication No.2001-107321 (FIG. 3)

Problems to be Solved

A conventional protective fence has the following problems to be solved.

[1] As disclosed in Patent Documents 1, 2, the protective fence havingthe plurality of supports arranged to stand in a non-inclinable manneris configured such that each support has a root fixed undisplaceably soas to withstand impact force and receive the transmitted impact force ata fixed position.

For this reason, a transmission time period over which impact force istransmitted from the protective net to each support is extremely short,and the impact force acts instantaneously on the support. As a result, aroot portion of the support is suddenly bent before theimpact-absorption capability possessed originally by the protectivefence is exerted, and such a capability cannot be fully exerted.

[2] In the protective fence having the plurality of supports arranged tostand in an inclinable manner disclosed in Patent Documents 3, 4 isconfigured such that each support is inclined upon reception of impact.However, impact force acts instantaneously on the root portion of thesupport, and as a result, the impact-absorption capability possessedoriginally by the protective fence cannot be fully exerted.

[3] A general protective fence having a flexible structure is providedwith a plurality of shock absorbers, and is configured such that impactforce is absorbed by operations of such plurality of shock absorbers.

Impact-absorption capability of the protective fence is improved byusing such plurality of shock absorbers; however, there is a need of theexchange or maintenance of members deformed after reception of impact.

SUMMARY OF THE INVENTION

The present invention is made so as to solve the problems describedabove, and an object thereof is to provide a structure having supportsarranged uprightly of a protective fence capable of relaxing stressconcentration on bottom portions of the supports, upon reception ofimpact, so as to prevent early deformation and buckling of the supports,thereby fully exerting impact-absorption capability possessed originallyby the protective fence.

Means for Solving Problems

One aspect according to the present invention is an uprightly-arrangedsupport structure of a protective fence, the protective fencecomprising: a plurality of supports arranged to stand at intervals, theplurality of supports having respective bottom portions thereof arrangedto stand via a ground plate on a slope; and a protective net spreadbetween the plurality of supports, wherein the bottom portions of theplurality of supports are arranged to stand so as to be slidable inconjunction with the ground plate in a predetermined direction on theslope.

In another aspect according to the present invention, a plurality ofslide holes are formed through the ground plate so that the ground plateis slidably fixed, through the plurality of slide holes, to a pluralityof anchors for ground plate, which are the same in number as theplurality of slide holes.

In still another aspect according to the present invention, theplurality of slide holes are formed so as to be parallel to one another,and such a plurality of parallel slide holes may be along an inclinationdirection of the slope, or may be along a direction orthogonal to theinclination direction of the slope, or may be along a direction slant tothe inclination direction of the slope.

In still another aspect according to the present invention, theplurality of supports and the ground plate may be of an assembly type,or may be integrally assembled in advance.

In still another aspect according to the present invention, theprotective net is mounted between an adjacent pair of the plurality ofsupports as a span unit.

Advantageous Effects of the Invention

According to the present invention, by arranging the bottom portions ofthe plurality of supports to stand slidably in conjunction with theground plate in the predetermined direction on the slope, the protectivefence is capable of relaxing stress concentration on the bottom portionsof the supports, respectively, upon reception of impact.

As a result, an early deformation and buckling of the supports can beprevented, and impact-absorption capability possessed originally by theprotective fence can be fully exerted.

BRIEF DESCRIPTIONS OF THE DRAWINGS

FIG. 1 depicts a perspective view of a protective fence, omitted partly,according to the present invention.

FIG. 2 depicts an exploded view of a support and a ground plateaccording to a first embodiment of the present invention.

FIG. 3 depicts a longitudinally cross-sectional view of the support andthe ground plate.

FIG. 4 depicts an explanatory view of the support and the ground plate,of which: (A) is a plan view of the ground plate ruptured partially; and(B) is a cross-sectional view of (A) at a line B-B.

FIG. 5 depicts an explanatory view of a protective-fence's actioncapturing falling objects, in the form of schematically planar view ofthe protective fence before the supports slide.

FIG. 6 depicts an explanatory view of a protective-fence's actioncapturing falling objects, in the form of schematically planar view ofthe protective fence at a time when the supports are allowed to slide.

FIG. 7 depicts a plan view of a ground plate, according to a secondembodiment of the present invention, which is perforated with slide slotholes formed in a Y-direction on a slope.

FIG. 8 depicts a plan view of a ground plate, according to a thirdembodiment of the present invention, which is perforated with slide slotholes formed in a slanting direction on a slope.

DESCRIPTIONS OF EMBODIMENTS OF THE INVENTION

Hereinafter, the present invention will be described with reference tothe accompanying drawings.

In the descriptions, the inclination direction of a slope G is definedas a Y-direction, and a direction orthogonal to the inclinationdirection of the slope G is defined as an X-direction.

First Embodiment [1] Outline of Protective Fence

Provided that the following explanations are made with reference to FIG.1, the present invention is based initially upon a protective fenceincluding a plurality of supports 10 (intermediate supports, terminalsupports) arranged to stand at predetermined intervals, and a protectivenet spread between the plurality of supports 10.

Provided that the following explanations are made about the protectivefence exemplified in an embodiment, each of the plurality of supports 10is arranged to stand via a ground plate 30 on a slope G.

The plurality of supports 10 have their respective bottom portionsslidable, in a predetermined direction on the slope G, in conjunctionwith the ground plate 30. Here, an embodiment having the plurality ofsupports 10 slidable in the X-direction on the slope G will bedescribed.

A sliding structure allowing the plurality of supports 10 to slide willbe described later.

A rope net 21 made of ropes and a wire mesh 22 smaller in mesh than therope net 21, which are superposed on each other, are bridged between theplurality of supports 10. A protective net 23 includes the rope net 21and the wire mesh 22.

An upper horizontal rope 21 a and a lower horizontal rope 21 b of therope net 21 are coupled, at their respective both ends, between anadjacent pair 10, 10 of the plurality of supports 10.

The rope net 21 may be mounted between adjacent two pieces of theplurality of supports 10 as a span unit, or may be mounted among threeor more pieces of the plurality of supports 10. In either of suchembodiments, a seam between left and right sides of the rope nets 21adjacent to each other is closed by coupling the left and right sideswith a separate accouplement (rope or the like) so as not to be opened.

Furthermore, an interval retention cord 24 made of ropes is routedbetween upper portions of an adjacent pair 10, 10 of the plurality ofsupports 10, as a span unit, so as to retain a constant interval betweenthe adjacent pair 10, 10.

The wire mesh 22 may be mounted to be suspended from the intervalretention cord 24, or may be mounted on the rope net 21.

A mountain-side anchor 40 is arranged immediately above each of theplurality of supports 10 or arranged in between an adjacent pair of suchsupports 10, and a lateral anchor 41 is arranged at a lateral side of aterminal support 10.

Known anchors such as ground anchors and lock bolts are applied to suchanchors 40, 41.

A mountain-side stay rope 45 is routed between an upper portion of eachof the plurality of supports 10 and the mountain-side anchor 40, and amountain-side positioning rope 46 is routed between each ground plate 30and the mountain-side anchor 40.

A lateral stay rope 47 is routed between an upper portion of theterminal support 10 and the lateral anchor 41, and a lateral positioningrope 48 is routed between a bottom portion of the terminal support 10and the lateral anchor 41.

In this embodiment, explanations are made about a protective fence of atype that the stay ropes 45, 47, and the rope net 21 including thehorizontal ropes 21 a, 21 b are not provided with known shock-absorbingmetal fittings; however, such an explained embodiment is also applicableto a protective fence provided with the shock-absorbing metal fittings.

[2] Support

Provided that the following explanations are made with reference toFIGS. 2-4, each of the plurality of supports 10 has slippage fasteningpins 11 provided in a protruding manner, on outer peripheries at theupper and bottom portions of such supports 10, which slippage fasteningpins 11 serve the purpose of fastening the interval retention cord 24,stay ropes 45, 47, and positioning rope 48 shown in FIG. 1 in an engagedstate while they are wound around the outer peripheries.

Coupling means for such a plurality of ropes is not limited to a type offastening by such slippage fastening pins 11. A bracket (not shown)provided in a protruding manner on each of the plurality of supports 10to be coupled with the plurality of ropes may be alternatively applied.

An embodiment having the plurality of supports 10 each formed of ahollow tube body (a steel tube or the like) is described here; however,the plurality of supports 10 include known supports such as known steelmembers (H-steel and the like) and concrete-filled steel tubes.

[3] Ground Plate

The ground plate 30 is a load-transmitting plate for transmitting anacting load through the plurality of supports 10 to the slope G forload-bearing capacity, while positioning the bottom portions of theplurality of supports 10.

The ground plate 30 has an outer cylinder 31 provided uprightly from itsupper surface, and the bottom portion of each support 10 is insertableinto the outer cylinder 31 so that it can be inscribed in a cylindricalrubber plate 32 on an inner periphery of the outer cylinder 31.

The outer cylinder 31 is ribbed with a plurality of reinforcing ribs 34arranged in a radial manner.

The bottom portion of each support 10 can be assembled with the groundplate 30 in such a manner that the bottom is inserted into cylindricalrubber plate 32 so as to be fit onto an inner periphery of thecylindrical rubber plate 32.

The outer cylinder 31 and the cylindrical rubber plate 32 may be in theform of a complete cylindrical body; however, they may also be in theform of a cylindrical-like body divided by vertical splits asillustrated in the relevant figures.

An embodiment with the plurality of supports 10 and the ground plate 30configured to be of an assembly type is described here, for the purposeof facilitating conveyance of material to a job site and improvingworkability at the job site; however, the plurality of supports 10 andthe ground plate 30 may be configured, as an alternative embodiment,such that they are coupled by fixing means such as welding or screwing.

It is to be noted that: an embodiment having the ground plate 30 with aconnection hook 36 to be coupled with an end of the mountain-sidepositioning rope 46 is shown here; however, such an end of themountain-side positioning rope 46 may be fastened by and coupled withthe bottom portions of the plurality of supports 10 in a direct manner.

[4] Tension Structure of Support and Ground Plate

Provided that the following explanations are made with reference toFIGS. 2-4, each of the plurality of supports 10 is configured such thatit is coupled in a tension state, via a tension member 50 insertedtherethrough, to the ground plate 30.

The tension member 50 is a rope member insertable through each support10, and has a bottom portion thereof fastened to a hanging hook 35provided to stand in an upright position from the bottom surface ofouter cylinder 31 on the ground plate 30.

The tension member 50 has a fastening bolt 51 connected integrally tothe upper portion thereof, and the fastening bolt 51, through which anannular back plate 52 and a spring 53 mounted in order on an upper endof each support 10 are inserted, is screwed on by a fastening nut 54.

The tension member 50 is tensioned by tightening the fastening nut 54,and as a result, each support 10 and the ground plate 30 are clamped sothat each support 10 can be maintained in an upright position withrespect to the ground plate 30 is maintained.

The ground plate 30 may be laid so as to contact directly a surface ofthe slope G; however, such a ground plate 30 is improved in stabilityand bearing-pressure effect when it is placed on a mortar layer 44 forheight adjustment constructed in advance on a surface of the slope G.

[5] Sliding Structure of Ground Plate

The ground plate 30 is fixed to the slope G such that it is allowed toslide in the X-direction on the slope G upon reception of impact. Asliding structure of the ground plate 30 will be described in detailwith reference to FIGS. 2-4.

[5.1] Slide Hole of Ground Plate

Regarding the sliding structure of the ground plate 30, a plurality ofslide slot holes 33, 33 are formed through the ground plate 30 in suchan arrangement that the outer cylinder 31 is interposed therebetween ona plate surface of the ground plate 30. The plurality of slide slotholes 33, 33 are arranged in parallel to one another as well as parallelto the X-direction on the slope G.

A sliding distance of the ground plate 30 is determined on the basis ofan entire slot length of the slide slot hole 33, and for this reason,the entire slot length of the slide slot hole 33 is selectedappropriately in consideration of the impact-absorption capability ofthe protective fence, the installation situation of the job site, andthe like.

[5.2] Anchor for Ground Plate

An anchor for ground plate 42 for fixing the ground plate 30 is a knownanchor such as a lock bolt, and is arranged at a plurality of positionsalong the Y-direction on the slope G.

The installation number of the anchor for ground plate 42 is requestedto be the same as that of the slide slot holes 33.

A screw to be screwed on by a nut 43 is formed on an above-groundexposed portion of the anchor for ground plate 42, and by screwing sucha nut 43 on such a screw on the above-ground exposed portion insertedthrough each of the slide slot holes 33, the ground plate 30 is fixed tothe slope G

Behavior of Protective Fence

Descriptions will be made on the behavior of the protective fence, thebehavior of the plurality of supports 10 in particular, at the time ofreception of impact with reference to FIGS. 5, 6. The basic actioncapturing falling objects such as falling rocks by the protective fenceis the same as that of conventional techniques, and for this reason,descriptions thereof will be omitted herein.

[1] Behavior of Support Immediately After Reception of Impact

FIG. 5 shows a schematic planar view of the protective fence immediatelyafter impact F of a falling object is received by the protective net 23,where the slide slot hole 33 of each ground plate 30 is arranged inparallel to the X-direction on the slope G.

Immediately after the impact F acts on the protective net 23, theprotective net 23 starts being deformed in a swelling manner toward avalley side, and also the impact F acts, as tensile force f, on each ofadjacent pair of supports 10, 10 through the protective net 23. Thetensile force f on each support 10 acts, as displacement force f, on theground plate 30 in the X-direction on the slope G.

When the displacement force f acting on the ground plate 30 in theX-direction on the slope G is smaller than the fixing strength of theground plate 30 fixed through the anchor for ground plate 42, nodisplacement occurs for the ground plate 30. In other words, thearranged positions of the adjacent pair of supports 10, 10 do not changefrom the beginning, and also, a span L₁between the adjacent pair ofsupports 10, 10 does not change.

Accordingly, as in the case of the conventional protective fences, animpact energy is absorbed with the deformation resistance of theprotective net 23 and the strength of each support 10.

[2] Sliding of Support

FIG. 6 shows a schematic planar view of the protective fence when adeformation amount of the protective net 23 is increased.

When the deformation amount of the protective net 23 is increased, thedisplacement force f acting on the ground plate 30 in the X-direction onthe slope G is also increased.

When the displacement force f acting on the ground plate 30 in theX-direction on the slope G exceeds the fixing strength of the groundplate 30 fixed through the anchor for ground plate 42, the ground plate30 is displaced in the X-direction on the slope G along the slide slothole 33.

In other words, the arranged positions of the adjacent pair of supports10 are displaced sideways from the positions at the beginning, and also,a span L₂ between the adjacent pair of supports 10, 10 becomes slightlyshorter in comparison with the span L₁ before the displacement.

Even during the displacement of the bottom portion of each support 10 inthe X-direction on the slope G, the impact energy is continuouslyabsorbed as an impact absorber energy by the deformation resistance ofthe protective net 23 and the strength of each support 10.

In this manner, in an embodiment according to the present invention, theduration of load acting against each support 10 is made longer byaccompanying the sliding displacement of each support 10 at a time whenimpact is received. It is possible, therefore, to avoid instantaneousaction of a whole impact F on the adjacent pair of supports 10, 10.

A longer time period over the action of load means that impact force isgradually applied to each support 10.

Accordingly, it is possible not only for each support 10 to fully exertthe originally possessed impact-absorption capability but also for theprotective net 23 to fully exert is own impact-absorption capacity.

In other words, stress concentration on the bottom portion can berelaxed as well as sudden bending of the root portion can be prevented,with respect to each support 10.

[3] Propagating Action on Adjacent Span

Once a falling object hits a portion of the protective net 23, theprotective net 23 positioned within the range of the impact is bent anddeformed toward a valley side so that impact energy is absorbed by thebending deformation resistance of the protective net 20.

When the deformation amount of the protective net 23 is increased, theadjacent pair of supports 10, 10 are displaced mutually in anapproaching direction, and the displacement force is propagated to somesupports 10 not shown such that such supports 10 are sequentially drawnvia the protective net 23 positioned exteriorly.

As a result, a span, which does not receive the impact, also performsthe function of absorbing impact energy.

Second Embodiment

Hereinafter, other embodiments will be described in such a manner thatthe same portions as the above-described embodiments are provided withthe same reference numerals, and detailed descriptions thereof areomitted.

Descriptions will be made, with reference to FIG. 7, on an embodimenthaving a bottom portion of the plurality of supports 10 is arranged soas to be slidable along the Y-direction on the slope G.

In this embodiment, a plurality of slide slot holes 33 are formedthrough the ground plate 30 in such an arrangement that: the pluralityof slide slot holes 33 are along the Y-direction on the slope G; and asin the case of previous Embodiment 1, the plurality of slide slot holes33 are parallel to one another on a plate surface of the ground plate30.

As in the case of previous Embodiment 1, the plurality of slide slotholes 33 are in parallel relation.

As in the case of previous Embodiment 1, the ground plate 30 is fixedvia the anchor for ground plate 42.

In this embodiment, at a time when impact is received, the bottomportion of each support 10 is slidable along the Y-direction on theslope G in conjunction with the ground plate 30 as a pressing plate. Asin the case of previous Embodiment 1, by accompanying a slidingdisplacement of each support 10 upon reception of impact, stressconcentration on the bottom portion of each support 10 can be relaxed,and the impact-absorption capability originally possessed by theprotective fence can be fully exerted.

Third Embodiment

Descriptions will be made, with reference to FIG. 8, on an embodimenthaving a bottom portion of the plurality of supports 10 is arranged soas to be slidable along a direction slant to a direction on the slope G.

In this embodiment, a plurality of slide slot holes 33 are formedthrough the ground plate 30 in such an arrangement that the plurality ofslide slot holes 33 are along the direction slant to a direction on theslope G.

In this embodiment, at a time when impact is received, the bottomportion of each support 10 is slidable along the direction slant to thedirection on the slope G in conjunction with the ground plate 30 as apressing plate. As in the case of previous Embodiments 1, 2, byaccompanying a sliding displacement of each support 10 upon reception ofimpact, stress concentration on the bottom portion of each support 10can be relaxed, and the impact-absorption capability originallypossessed by the protective fence can be fully exerted.

Reference Numerals

-   10 support-   11 slippage fastening pin-   21 rope net-   21 a upper horizontal rope-   21 b lower horizontal rope-   22 wire mesh-   23 protective net-   24 interval retention cord-   30 ground plate, pressing plate-   31 outer cylinder-   32 cylindrical rubber plate-   33 slide slot hole-   34 reinforcing rib-   35 hanging hook-   40 mountain-side anchor-   41 lateral anchor-   42 anchor for ground plate-   43 nut-   45 mountain-side stay rope-   46 mountain-side positioning rope-   47 lateral stay rope-   48 lateral positioning rope-   50 tension member-   51 fastening bolt-   52 back plate-   53 spring-   54 fastening nut

What is claimed is:
 1. An uprightly-arranged support structure of a protective fence, the protective fence comprising: a plurality of supports arranged to stand at intervals, the plurality of supports having respective bottom portions thereof arranged to stand via a ground plate on a slope; and a protective net spread between the plurality of supports, wherein the bottom portions of the plurality of supports are arranged to stand so as to be slidable in conjunction with the ground plate in a predetermined direction on the slope.
 2. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein a plurality of slide holes are formed through the ground plate so that the ground plate is slidably fixed, through the plurality of slide holes, to a plurality of anchors for ground plate, which are the same in number as the plurality of slide holes.
 3. The uprightly-arranged support structure of the protective fence, according to claim 2, wherein the plurality of slide holes are formed so as to be parallel to one another along an inclination direction of the slope.
 4. The uprightly-arranged support structure of the protective fence, according to claim 2, wherein the plurality of slide holes are formed so as to be parallel to one another along a direction orthogonal to an inclination direction of the slope.
 5. The uprightly-arranged support structure of the protective fence, according to claim 2, wherein the plurality of slide holes are formed so as to be parallel to one another along a direction slant to an inclination direction of the slope.
 6. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein the plurality of supports and the ground plate are of an assembly type.
 7. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein the plurality of supports and the ground plate are integrally assembled in advance.
 8. The uprightly-arranged support structure of the protective fence, according to claim 1, wherein the protective net is mounted between an adjacent pair of the plurality of supports as a span unit. 